E) THz Laboratory

The THz lab is located in the Sommerfeld-Keller, the place where Max von Laue did his pioneering experiments on X-ray diffraction around 1910. Today, our goal is to measure ultrafast electron dynamics by time-resolved THz spectroscopy. The THz pulses are generated with a femtosecond laser. Electrooptic detection of the THz pulses visualizes the evolution of the electromagnetic field directly in the time-domain. The observation of electronic dynamics requires a high level of precision and reproducibility. Thus, most of the equipment and techniques are either encapsulated or integrated into vacuum chambers.

Femtosecond laser equipment

Fig 1: The femtosecond Mai Tai laser

• Ti:Sapphire laser (Mai Tai):
• pulse duration: 60 fs
• tunability: 790 nm - 810 nm

The basic experimental principle used for THz time-domain spectroscopy is electro-optic sampling (see webpage of  Prof. Zhang's group). The entire setup is integrated into a vacuum chamber to ensure measurements free of disturbing influences due to water absorption.

Fig 2: Experimental setup for THz time-domain spectroscopy. The red arrow indicates where the THz microscope is located.

Fig 3: Setup for THz spectroscopyTHz